U.S. Tornado Count “Average” So Far

Chart of U.S. Annual Tornado Count (click for larger view)

Chart of U.S. Annual Tornado Count (click for larger view)

With eastern Iowa experiencing its first tornado of the year, I thought it was important to take a look at exactly how this year is shaping up, at least so far.  The Storm Prediction Center in Norman, Oklahoma reports since January 1st, an estimated 358 tornadoes have touched down.  That number is almost right in line with the 2004-2008 average.  In most studies, you would think that average base is quite small.  But there’s a reason for that.

Intricate tornado records date back to 1950.  Since then, the number of tornadoes reported in the U.S. has increased dramatically.  Not because of dramatic changes in the atmosphere or some anomaly, primarily because of stormchasing.  A vast network of chasers fan out in almost any organized severe weather event.  Add the advances in doppler radar and meso detection and you make it nearly impossible for a tornado to touch down and go unnoticed.  So it’s only practical to keep the average base down to a few recent years.

Within those average years, 2004 saw the highest number of tornadoes.  But what is interesting of note is that you can also see a large spike in late May and early June for tornadoes in 2008.  Many in eastern Iowa will remember this period of high tornado activity included both the EF-5 tornado which struck Parkersburg and New Hartford.  It also includes another deadly tornado which struck western Iowa in mid-June.

For now, all that can be said about this tornado season is that it appears average, but the chart cleary shows average can quickly become active or quiet.  In the coming days I will blog about a new effort to increase our understanding of severe weather and tornadoes, the second installment of Project Vortex.  It’s an ambitious study using an army of stormchasers and it’s the first such study conducted in 13 years.  Project Vortex II launches in just under two weeks.  For more, check back in the coming days.

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